Methods and systems for air compressor and engine driven control

ABSTRACT

Power systems and methods of controlling an engine driven air compressor include an air compressor driven by an engine via a clutch. A first pressure sensor configured to sense a pressure level at an outlet of the air compressor. An inlet valve configured to close in response to the first pressure sensor sensing a pressure level above a first pressure level. In addition, a second pressure sensor to sense a pressure level below a second pressure level at a housing of the air compressor, wherein the clutch is configured to disengage in response to the second pressure level, wherein the first pressure level is higher than the second pressure level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/810,824, entitled “METHODS AND SYSTEMS FOR AIR COMPRESSOR AND ENGINEDRIVEN CONTROL,” filed Nov. 13, 2017, which is hereby incorporated byreference in its entirety for all purposes.

BACKGROUND

Conventionally, engine-driven power systems are configured to powermultiple components, such as generators, air compressors, welders, toname but a few. Many different types of power systems exist with avariety of components and functions, such as home-standby generators,portable generators and/or welders, and portable air compressors.

Some engine driven air compressors are either driven at all times by adirect continuous, connection with the engine, or intermittently via aclutch or other variable and/or disconnecting member. However, suchpower systems can consume large amounts of fuel, require frequentmaintenance, and cause environmental noise and exhaust during operation.Thus, an engine-driven power system to drive an air compressor thatmitigates these negative effects is desirable.

SUMMARY

Engine driven power systems and methods for an improved air compressorcontrol are disclosed, substantially as illustrated by and described inconnection with at least one of the figures. In particular, a system tocontrol an air compressor and/or an engine based on a sensed airpressure at the air compressor to reduce a load on the engine isprovided herein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a functional diagram of an example power system, in accordancewith aspects of this disclosure.

FIG. 2 illustrates an example control circuit to control a compressor ofa power system, in accordance with aspects of this disclosure.

FIG. 3 illustrates an example method of operating a power system, inaccordance with aspects of this disclosure.

FIG. 4 illustrates an example pneumatic control for an air compressor,in accordance with the present disclosure.

FIG. 5 is a functional diagram of another example power system, inaccordance with aspects of this disclosure.

FIG. 6 illustrates another example method of operating a power system,in accordance with aspects of this disclosure.

The figures are not necessarily to scale. Where appropriate, similar oridentical reference numbers are used to refer to similar or identicalcomponents.

DETAILED DESCRIPTION

Conventionally, engine driven generators and air compressors systems areeither driven at all times by a direct, continuous connection with theengine, or intermittently via a clutch or other variable and/ordisconnecting member.

Air compressors that turn continuously may be configured to stopproducing air when pressurized output is not needed. Cessation of outputfrom such air compressors can be achieved in a variety of ways, such asby closing the air compressor inlet, or diverting the unused air to beexhausted to the atmosphere. Both procedures allow the compressor tospin while consuming less energy. With the decreased load, less energyis required such that conventional systems may idle the engine with theair compressor load still connected.

In the example of a fixed throttle air compressor driven by the engine,this idle speed varies depending on the engine temperature andcompressor load, which are both variables dependent on ambienttemperature, system temperature, operating conditions of the components,etc. However, if an electric generator is also coupled to the engine,for example, the variable idle speed can create problems as theresulting electrical power produced can vary, causing unpredictable weldstarts and a less responsive engine. In addition, the fuel consumptionremains high because of the continuing load from the compressor even asthe engine is rotating at an idle speed. Such conventional systemstypically do not operate with other airflow controls, since the aircompressor is either on or off.

Compressors that are configured to be disconnected from the engine havethe advantage of turning on and off as needed. This is of particularvalue for engines configured to power other devices, such as agenerator. For example, if only output from the generator is needed, thecompressor can be turned off. If an output is needed (e.g. pressurizedair), the clutch can engage the compressor and activate airflow toprovide pressurized air as needed.

For a reciprocating type compressor, the clutch cycles on and off toincrease air pressure within an air tank, or housing, as need. Thisfunction can be controlled by a pressure switch in the air tank. For arotary screw compressor, the clutch can be cycled by a pressure switchin the air tank, or if no tank is being used, a control scheme candetermine the timing and operation of the throttle at the air inlet tomeet output demand. For instance, the inlet throttle control can be apneumatic proportional control valve that closes the inlet when outletpressure meets a target pressure level. The proportional control canalso be configured to partially open the inlet to control flow levels,as well as opening fully to allow maximum flow at the inlet. The inletthrottle control can also be an electric control which closes the inletvalve when a pressure switch or sensor identifies a predetermined level,and opens the valve with a different (e.g., lower) pressure. Partialflow can, however, be controlled by an electric controller.

Both the proportional and electric control systems used in rotary screwtype air compressors keep the compressor at full pressure, yet providingno output flow, when no output air is needed. Operating in this mode,however, consumes a high amount of power (i.e., requires significantfuel consumption) as, even though the pump is not pumping air for anoutput, the pump is spinning against a high differential pressure. Thedifferential pressure is the case pressure (e.g., built up pressurewithin the housing) of the compressor which is at the output setpressure (e.g., about 150 pounds per square inch (psi)), less the inletto the pump which is at a near vacuum (e.g., about −14 psi).

Furthermore, idling the engine with the high, no-flow load of the rotaryscrew compressor does not work with a fixed engine throttle position forsmall, gas-powered engines. This is due to the fact that the enginethrottle cannot open enough to maintain an idle speed.

To improve upon conventional designs, this disclosure relates toconfigurations and operation of a compressor (e.g., an air compressor)in an engine driven system to mitigate negative effects of theconventional system. For example, the presently disclosed systemsimprove upon the conventional systems by allowing the engine andgenerator to be coupled to the compressor by a clutch. Thisconfiguration results in a compact, cost effective, and reliable system,with the compressor to be driven by the engine.

The system can be housed in an enclosure, the engine being a source ofmechanical power, with the compressor utilizing that power to provideoutput in the form of compressed air. The mechanical power of the engineis transferred to the air compressor via a clutch, belt, idler pulley,compressor pulley, etc., which is directly connected to the enginecrankshaft. In some examples, the engine is directly coupled to anelectric generator to generate electrical power.

In some examples, the air compressor is a rotary screw type compressordriven by the engine. A rotary screw compressor is a type of gascompressor that uses a rotary type positive displacement mechanism. Theyare used to replace piston compressors where large volumes ofhigh-pressure air are needed, such as for construction or industrialapplications. The gas compression process of a rotary screw is acontinuous sweeping motion, so the pressure build up is generally smoothrelative to a piston compressor. Additionally, rotary screw compressorsare relatively compact and operate smoothly with limited vibration. Somerotary screw compressors are characterized as oil-injected, wherelubricating oil aids in sealing and cooling functions.

In disclosed examples, a method of controlling an engine driven aircompressor is provided, which includes measuring, at a first pressuresensor, a first pressure level that exceeds a threshold pressure levelat an outlet of the air compressor, adjusting an inlet valve of the aircompressor in response to the first pressure level in order to limit anamount of air from being introduced into the air compressor from pumpingair, measuring, at a second pressure sensor, a second pressure levelthat is lower than the first pressure level, and controlling, via acontroller, a clutch to disengage in response to the second pressurelevel, the clutch configured to transfer power from an engine to the aircompressor.

In examples, the method includes activating a bleed down valve inresponse to the first pressure level, which in turn controls the inletvalve to adjust.

In examples, the method includes measuring a duration of time duringwhich the clutch of the air compressor is disengaged, determining, atthe controller, that the duration exceeds a threshold time, andcontrolling, via the controller, the engine to idle in response to thedetermination. In examples, the method includes controlling, by thecontroller, the engine to idle at a constant speed in response to thedetermination.

In examples, the method includes, in response to the first sensormeasuring a pressure level below the threshold pressure level,controlling, via the controller, the inlet valve to open, andcontrolling, via the controller, the clutch to engage.

In examples, the method includes deactivating the bleed down valve inresponse to measuring the pressure level below the threshold pressurelevel, which in turn controls the inlet valve to open. In examples, thefirst pressure sensor is configured to be adjusted by a user to set thethreshold pressure level.

In examples, the first pressure sensor is one of a pressure transduceror a pressure switch configured to generate a signal in response to thefirst pressure level, the controller further configured to receive, atthe controller, the signal; and control, via the controller, the inletvalve in response to the signal.

In other disclosed examples, a power system includes an air compressordriven by an engine via a clutch, a first pressure sensor configured tosense a pressure level at an outlet of the air compressor, an inletvalve configured to close in response to the first pressure sensorsensing a pressure level above a first pressure level, and a secondpressure sensor to sense a pressure level below a second pressure levelat a housing of the air compressor, wherein the clutch is configured todisengage in response to the second pressure level, wherein the firstpressure level is higher than the second pressure level.

In examples, the system includes a bleed down valve configured to reducethe pressure within the air compressor in response to the first pressurelevel, which reduces the differential pressure and reduces the powerneeded to drive the air compressor.

In examples, the system includes an electric generator driven by theengine via a generator clutch, the generator clutch to drive theelectric generator independently of the air compressor.

In examples, the controller is further configured to measure a durationof time during which the clutch of the air compressor is disengaged,determine whether the duration exceeds a threshold time duration, andcontrol the engine to idle in response to a determination that the timeduration exceeds the threshold time duration.

In examples, the controller is further configured to determine whetherthe engine is driving an electric generator, and control the engine toidle in response to determinations that the time duration exceeds thethreshold time duration and the engine is not driving the electricgenerator. In examples, the threshold time duration is between 30seconds and 2 minutes.

In yet additional examples, a welding-type power system controls anengine driven air compressor, the system includes a pressure sensorconfigured to measure a pressure level that exceeds a first pressurelevel at an outlet of the air compressor, an inlet valve of the aircompressor configured to close in response to the pressure level inorder to stop air from being introduced into the air compressor, and acontroller. The controller is configured to activate a timer, anddisengage a clutch in response to expiration of the timer, the clutchconfigured to transfer power from the engine to the air compressor.

In examples, the system includes a bleed down valve configured toactivate in response to the first pressure level, which in turn controlsthe inlet valve to close, wherein the bleed down valve lowers thepressure level in the air compressor from the first pressure level to asecond pressure level.

In examples, in response to the first sensor sensing a pressure levelbelow the first pressure level, the bleed down valve is furtherconfigured to close, the inlet valve is configured to open, and theclutch is configured to engage. In examples, the first pressure sensoris a transducer having an adjustable pressure range.

In examples, the controller is further configured to receive signalsfrom the transducer corresponding to the first or second pressurelevels, and control one or more of the bleed down valve, the inletvalve, the clutch, or the engine in response to the signals. Inexamples, the time to expiration is between 30 seconds and 2 minutes. Insome examples, the engine is configured to idle at a constant speed. Insome examples, the first pressure is about 150 psi.

In yet other examples, a welding-type power system includes a rotaryscrew air compressor driven by an engine via a clutch.

As used herein, the term “welding-type power” refers to power suitablefor welding, plasma cutting, induction heating, CAC-A and/or hot wirewelding/preheating (including laser welding and laser cladding). As usedherein, the term “welding-type power supply” refers to any devicecapable of, when power is applied thereto, supplying welding, plasmacutting, induction heating, CAC-A and/or hot wire welding/preheating(including laser welding and laser cladding) power, including but notlimited to inverters, converters, resonant power supplies,quasi-resonant power supplies, and the like, as well as controlcircuitry and other ancillary circuitry associated therewith.

As used herein, a “circuit” includes any analog and/or digitalcomponents, power and/or control elements, such as a microprocessor,digital signal processor (DSP), software, and the like, discrete and/orintegrated components, or portions and/or combinations thereof.

As used herein, the terms “first” and “second” may be used to enumeratedifferent components or elements of the same type, and do notnecessarily imply any particular order. For example, while in someexamples a first compartment is located prior to a second compartment inan airflow path, the terms “first compartment” and “second compartment”do not imply any specific order in which airflows through thecompartments.

FIG. 1 is a functional diagram of an example power system 100. Thesystem 100 is an engine-driven power system, which includes an engine104 that drives an air compressor 102 (e.g., a rotary screw type aircompressor). The air compressor 102 is driven by the engine 104 via aclutch 106. The clutch 106 is configured to engage and or disengage theair compressor 102 based on one or more sensed conditions, as describedherein. For example, the air compressor 102 can include one or moresensors to sense and/or measure a pressure at one or more locationswithin the system. Sensors can also be used to indirectly measurevariables such as airflow, changes in temperature, forces acting onhousings, among others. The sensors can be any type of sensor configuredto measure a pressure, including analog and digital sensors, forcecollector type sensors such as piezo-resistive strain gauge,piezoelectric, optical fiber based sensors, potentiometric thermalsensors, transducers, pressure indicators, piezometers, manometers, toname but a few.

In the example of FIG. 1, a first sensor 108 and a second sensor 110measure pressure(s) within a housing/tank of the air compressor 102, atan outlet, an inlet, and/or another location of the air compressor 102.In some examples, a bleed down valve 112 is included to moderate apressure within the air compressor 102 housing. The bleed down valve 112controls a compressor inlet valve 111 and to slowly reduce pressure inthe compressor case when the inlet valve 111 is closed. In examples, acontroller 114 is configured to monitor and/or control one or moreconditions of the system 100. For instance, the controller 114 receivesinformation from each of the first and second sensors 108, 110, as wellas other operating parameters (e.g., temperature, rotation speed of oneor both of the compressor 102 and engine 104, etc.) of the system 100.

In some examples, an electrical generator 120 is connected to the engine104 to provide one or more types of electrical power suitable forspecific and/or general purpose uses, such as welding-type power, 110VAC and/or 220 VAC power, battery charging power, and/or any other typeof electrical power. Furthermore, the example system 100 may includeother components not specifically discussed herein.

In some examples, the system 100 employs a controller 114 forcontrolling an output of the air compressor 102. For instance, thecontroller 114 can engage the clutch 106 to operate at variable speedsin response to the speed of the engine 104, operate one or more valvesto release pressure from the air compressor 102, as well as controllingthe engine 114 to idle, such as when the compressor 102 is not in use.Additionally or alternatively, a user interface 118 can be employed toallow a system operator to adjust one or more parameters associated withthe system 100. For example, one or more predetermined pressure levelsand/or ranges can be adjusted via the user interface 114 to accommodatea particular operation or need. The user interface 118 can be integratedwith and/or located remotely from the air compressor 102 and/or thecontroller 114.

In another example, the system 100 employs one or more transducers 109configured to measure a first pressure level at an outlet of the aircompressor and a second pressure level at a housing of the aircompressor. The transducer 109 can measure pressure levels at the outletvalve 116 and the housing of the compressor, and transmit theinformation to the controller 114. The transducer 109 is configured totransmit a signal indicating the pressure level to the controller 114via one or more circuits. The controller 114 can be configured tocontrol the bleed down valve 112 (e.g., a solenoid valve), and/or theinlet valve 111, to activate in response to the first pressure levelbeing above a first, high-pressure level as indicated by the signal fromthe transducer 109. Further, the controller 114 can control the clutch106 to disengage in response to the second pressure level being below asecond, low-pressure level. In this example, the transducer 109 is ableto sense the pressure at multiple locations, such as by alternatingmeasurements, and the controller 114 is capable of analyzing the signalsfrom the transducer 109 to determine the appropriate control. In thismanner, the transducer 109 can be used in addition to or as a substitutefor the first and second sensors 108, 110.

FIG. 2 illustrates an example control circuit 200 to operate an enginedriven air compressor. In some examples, the control circuit 200 mayimplement and/or be integrated into the controller 114 of FIG. 1. Insome examples, the control circuit 200 is a wholly separate controllerconfigured to respond to changes in pressure and control the systemcomponents, as described with respect to FIG. 1. Where the circuit 200incorporates components common to FIG. 1, similar numbering will be usedto simplify descriptions of the figures.

The example circuit 200 responds to changes in the pressure level at thecompressor 102, as described with respect to FIG. 1. In response tochanges in the pressure level, a first, high-pressure switch 202 (e.g.,the first sensor 108 of FIG. 1) and/or a second, low-pressure switch 204(e.g., the second sensor 110 of FIG. 1) can change in state to controloperation of the compressor 102, clutch 106, and/or the engine 104.Additionally or alternatively, an over pressure switch 208 and an overtemperature switch 210 can be configured to activate in response tohigh-pressure and/or temperature levels at the compressor 102 andgenerate a signal to a controller (e.g., controller 114, a printedcircuit board (PCB), etc.) to mitigate damage therefrom. Additionally oralternatively, a compression switch 206 is available to an operator toturn the compressor on and off to engage or disengage the circuitdescribed with respect to FIG. 2.

In examples, when the pre-determined pressure is reached (e.g., 150psi), the high-pressure switch 202 activates to open the electric bleeddown valve 112. The bleed down valve 112 applies case pressure to closethe inlet valve 111 and stop the compressor 102 from pumping air. At thesame time, the bleed down valve 112 starts to relieve the compressorcase or housing pressure through an outlet and/or valve. This bleed offslowly reduces pressure inside the compressor case which reduces thedifferential pressure and thus the no-flow power required to turn thecompressor 102.

The outlet check valve 116 keeps air pressure downstream of thecompressor 102 as the compressor case pressure is reduced through thebleed down process, which can take from 30 seconds to 2 minutes. Thecircuit 200 is configured to sense or receive information indicatingthat the air output has not been used, and proceeds to idle the engine104 based on the information. The circuit 200 responds to thelow-pressure in the compressor case, indicated via deactivation of alow-pressure switch 204 that is configured to close at a pressure levelabout 30 psi. The bleed down rate, for example from 150 psi to 30 psi,is determined by a bleed down outlet and may take between 30 seconds and2 minutes to reach the desired pressure level. Once the low-pressurelevel is met in the compressor case, the clutch 106 to disengages inresponse.

In particular, as the compressor case bleeds down and pressure reducesto 30 psi, the low-pressure switch 204 deactivates which disengages thecompressor clutch 106. The clutch 106 disengages and this electricalsignal can be used to direct the engine 104 to enter into an idle mode.In examples where no load is on the engine 104, the engine 104 can idlewith a fixed engine throttle position idle system at a consistent andpredictable speed. With the clutch 106 disengaged, the compressor 102enters into a stand-by mode. For instance, stand-by mode corresponds tothe outlet pressure being maintained via the outlet check valve whilethe compressor 102 is at low or no pressure and disconnected from theengine 104. The compressor 102 is still on and restarts when airpressure at the outlet is reduced to the point the high-pressure switch202 closes. Thus, the bleeding down of the compressor pressure istriggered by the high-pressure switch 202 along with the de-clutchingand idling of the engine 104 triggered by deactivation of thelow-pressure switch 204.

When air is used (e.g., to operate an air drive tool), the compressor102 responds by starting to pump air again. When air is used, pressureat the high-pressure switch 202 drops and the switch changes state(e.g., closes). In response, the compressor clutch 106 engages and thebleed down valve 112 closes, which opens a compressor inlet valve 111allowing air into the now turning pump within the compressor 102.

Additionally or alternatively, the circuit of FIG. 2 is designed tore-start the compressor 102 from a stand-by mode, which is animprovement over conventional compressor control schemes. The compressor102 is configured to pump air until the high-pressure switch 202 reachesa set point or threshold level again, and the bleed down-to-idle processstarts over. However, if air output is used before the compressorpressure decreases enough to initiate idling (e.g., a case pressurebetween 30 and 150 psi), the high-pressure switch 202 closes in responseto the pressure drop, causing the inlet valve (e.g. inlet valve 111) toopen and the compressor 102 is activated to again pump air.

The systems and controls described with respect to FIGS. 1 and 2 allowthe compressor 102 to disengage and the engine 104 to idle with a fixedthrottle position idle feature. The controls and systems are relativelysimple in that only two pressure switches (e.g., high-pressure switch202, low-pressure switch 204) are used to provide both compressorpressure control as well as activation of a stand-by mode, which in turnis configured to idle the engine 104 when no load is present. Therefore,no alternate control system or logic (e.g., a processor or computercontrol) is needed, as the control system both satisfies output need aswell as reducing the load on the engine 104 by proceeding to a stand-bymode under certain conditions. In particular, a logic controller (e.g.,a processor or other type of instruction based microcontroller) is notneeded, as the circuit and system are configured to operate in responseto the changes in pressure measured at the high-pressure switch 202and/or low-pressure switch 204.

FIG. 3 is a flowchart illustrating example method 300 of controlling anengine driven air compressor, as described with respect to FIGS. 1 and2. In block 302, a first pressure sensor (e.g., the sensor 108) measuresa first pressure level at an outlet (e.g., the outlet 116) of the aircompressor (e.g., the air compressor 102).

In block 304, the first pressure level is compared to a predeterminedthreshold pressure level. If the first pressure level does not exceedthe predetermined threshold pressure level, block 304 will return toblock 302 in a loop to continuously monitor the pressure and othersystem parameters during implementation of the method. If the firstpressure level exceeds the predetermined threshold pressure level, themethod advances to block 306, where a bleed down valve (e.g., the bleeddown valve 112) activates in response.

In block 308, a second pressure sensor (e.g., the sensor 110) measures asecond pressure level. In block 310, the second pressure level iscompared to a predetermined threshold pressure level (e.g., a thresholdlow-pressure level). If the second pressure level does not fall belowthe predetermined threshold low-pressure level, block 310 will return toblock 308 in a loop to continuously monitor the pressure and othersystem parameters during implementation of the method. If the secondpressure level does fall below the predetermined threshold low-pressurelevel, a clutch (e.g., the clutch 106) is controlled to disengage froman engine (e.g., the engine 104) in response to the second pressurelevel in block 310.

Additionally or alternatively, at block 314, a duration of time can bemonitored and/or measured, during which the clutch of the air compressoris disengaged. The duration of time is compared against one or morethreshold time values at block 316. If the time does not exceed thethreshold, the method returns to block 314. If the time exceeds thethreshold time value, the controller controls the engine to idle atblock 318. Once the engine enters an idle speed, the method returns toblock 302 to continue monitoring the pressure levels at the compressoroutlet. Thus, once a demand for air pressure is measured, the engine canbe controlled to increase in speed (e.g., change from an idle speed toan operating speed), as well as engage the clutch and disengage thebleed down valve.

Additionally or alternatively, method 300 of FIG. 3 may be implementedby the controller 114 of FIGS. 1-2 by executing machine-readableinstructions, such as stored on a non-transitory machine-readablestorage device. In such an examples, the controller 114 can receiveelectronic signals from the system sensors (e.g., a transducer) andcontrol the system components based on a series of algorithms and/orcalculations consistent with the examples provided herein.

FIG. 4 illustrates an example pneumatic control 400 for an aircompressor, in accordance with the present disclosure. As shown in FIG.4, an inlet filter 402 is connected to an inlet valve 404 to allow airto flow into the compressor. A blowdown valve 406 is connected to ablowdown orifice 408. An adjustable first, high-pressure switch 414 isconfigured to measure a pressure level of the compressor. A minimumpressure control valve 416 incorporates a check valve to maintainpressure downstream during blowdown of the compressor case. The blowdownvalve 406 is configured to open in response to the high-pressure switch414 sensing a pressure above a predetermined threshold level. Onceactivated/opened, the blowdown valve 406 in turn closes the inlet valve404. For instance, the inlet valve 404 is pneumatically activated by theblowdown valve 406 to provide a timed pressure reduction of thecompressor case until the high-pressure switch 414 no longer senses thepressure level above the predetermined threshold level.

A second, low-pressure switch 412 is configured to sense a second,low-pressure level in the compressor case, which can in response controla clutch (e.g. clutch 106) to disengage from an engine (e.g., engine104). In particular, as the compressor case bleeds down and the pressurereduces to a predetermined level (e.g., 30 psi), the low-pressure switch412 deactivates/opens which disengages the compressor clutch. The clutchdisengages, which can also indicate that the engine is to enter into anidle mode.

If the pressure at the high-pressure switch 414 senses a pressure belowthe predetermined threshold level, the high-pressure switch 414 closes,which closes the blowdown valve 406 and in turn opens the inlet valve404. The clutch can also be engaged, such that the engine is capable ofturning the air compressor to increase pressure within the housing.

Additionally or alternatively, the pneumatic control 400 can include apressure relief valve 418 as a safety outlet, pressure gauge 420, and anover pressure switch 410. For example, when a pressure exceeds apredetermined level, an over pressure switch 410 activates whichdisengages the compressor clutch. A case temperature sensor 422 can alsoprovide information regarding a temperature in the air compressor.

FIG. 5 is a functional diagram of another example power system 500. Thesystem 500 is an engine-driven power system similar to the system 100,the system including an engine 504 that drives an air compressor 502 viaa clutch 506. The system 500 can include a user interface 518, agenerator 520, as well as other components described herein. In theexample of FIG. 5, a sensor 508 measures pressure(s) within ahousing/tank of the air compressor 502, at an outlet/outlet valve 516,an inlet, and/or another location of the air compressor 502. Acontroller 514 is configured to monitor and/or control one or moreconditions of the system 500.

Additionally, the system 500 includes a timer 510, such as a countdowntimer or other suitable timing device (e.g., incorporated with amicroprocessor, etc.), configured to activate in response to ahigh-pressure level being sensed by the sensor 508. In particular, inresponse to the sensor 508 sensing a high-pressure level above aparticular threshold level, a bleed down valve 512 controls a compressorinlet valve 511 to slowly reduce pressure in the compressor case uponclosure of the inlet valve 511. Simultaneously or in response to theclosure of the inlet valve 511, the timer 510 counts down apredetermined duration (e.g., between about 30 seconds and 2 minutes),which, upon expiry, can inform the controller 514 to disengage theclutch 506. Before disengaging the clutch 506, the controller 514determines if the pressure level has reset (e.g., the sensor 508 nolonger senses the high-pressure level). Thus, the timer 510 is reseteach time the sensor 508 indicates the high-pressure condition is nolonger present.

FIG. 6 is a flowchart illustrating another example method 600 ofcontrolling an engine driven air compressor, as described with respectto FIG. 5. In block 602, a pressure sensor (e.g., the sensor 508)measures a pressure level at an outlet (e.g., the outlet 516) of the aircompressor (e.g., the air compressor 502). In block 604, the pressurelevel is compared to a predetermined threshold pressure level. If thepressure level does not exceed the predetermined threshold pressurelevel, block 604 will return to block 602 in a loop to continuouslymonitor the pressure and other system parameters during implementationof the method. If the pressure level exceeds the predetermined thresholdpressure level, the method advances to block 606, where a bleed downvalve (e.g., the bleed down valve 512) activates in response.

In block 608, a timer (e.g., the timer 510) counts down a predeterminedamount of time. In block 610, the controller determines if the thresholdpressure level is still being exceeded, such that the sensor has notreset (e.g., which would cause the timer to rest). If the sensor and thetimer have reset, block 610 will return to block 608 in a loop tocontinuously monitor the pressure and other system parameters duringimplementation of the method. If the sensor and timer have not reset, aclutch (e.g., the clutch 506) is controlled to disengage from an engine(e.g., the engine 504) in response to expiration of the timer at block612.

Additionally or alternatively, at block 614, a duration of time can bemonitored and/or measured (e.g., by controller 514), during which theclutch of the air compressor is disengaged. The duration of time iscompared against one or more threshold time values at block 616. If thetime does not exceed the threshold, the method returns to block 614. Ifthe time exceeds the threshold time value, the controller controls theengine to idle at block 618. Once the engine enters an idle speed, themethod returns to block 602 to continue monitoring the pressure levelsat the compressor outlet. Thus, once a demand for air pressure ismeasured, the engine can be controlled to increase in speed (e.g.,change from an idle speed to an operating speed), as well as engage theclutch and disengage the bleed down valve.

Additionally or alternatively, block 612 proceeds directly to block 618to control the engine to idle, as shown by dotted line 620. In thisexample, the duration of time is not monitored by the controller, andthe engine is controlled to idle in response to expiration of thecountdown timer.

Additionally or alternatively, method 600 of FIG. 6 may be implementedby the controller 514 of FIG. 5 by executing machine-readableinstructions, such as stored on a non-transitory machine-readablestorage device. In such an examples, the controller 514 can receiveelectronic signals from the system sensors (e.g., a transducer) andcontrol the system components based on a series of algorithms and/orcalculations consistent with the examples provided herein.

As utilized herein, “and/or” means any one or more of the items in thelist joined by “and/or”. As an example, “x and/or y” means any elementof the three-element set {(x), (y), (x, y)}. In other words, “x and/ory” means “one or both of x and y”. As another example, “x, y, and/or z”means any element of the seven-element set {(x), (y), (z), (x, y), (x,z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means “one ormore of x, y and z”. As utilized herein, the term “exemplary” meansserving as a non-limiting example, instance, or illustration. Asutilized herein, the terms “e.g.,” and “for example” set off lists ofone or more non-limiting examples, instances, or illustrations.

While the present method and/or system has been described with referenceto certain implementations, it will be understood by those skilled inthe art that various changes may be made and equivalents may besubstituted without departing from the scope of the present methodand/or system. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the presentdisclosure without departing from its scope. For example, systems,blocks, and/or other components of disclosed examples may be combined,divided, re-arranged, and/or otherwise modified. Therefore, the presentmethod and/or system are not limited to the particular implementationsdisclosed. Instead, the present method and/or system will include allimplementations falling within the scope of the appended claims, bothliterally and under the doctrine of equivalents.

What is claimed is:
 1. A method of controlling an engine driven aircompressor, comprising: measuring, at a first pressure sensor, a firstpressure level that exceeds a first threshold pressure level at anoutlet of the air compressor; adjusting an inlet valve of the aircompressor in response to the first pressure level in order to limit anamount of air from being introduced into the air compressor; measuring,at a second pressure sensor, a second pressure level; controlling aclutch to disengage in response to the second pressure level fallingbelow a second threshold pressure level, the clutch configured totransfer power from the engine to the air compressor; measuring aduration of time during which the clutch of the air compressor isdisengaged; determining, at a controller, that the duration exceeds athreshold time; and controlling, via the controller, the engine to idlein response to the determination.